however when two folk attack you its not much use trying to grapple one on the floor to submission as the other will beat you senseless.
That’s not true at all actually. Granted, you absolutely don’t want to be in that situation but there’s a myriad of dominant positions you can get one person into leaving you to deal with another, or essentially shield yourself with your assailant.
When I was doing JKD (circa 1999) I had this debate with a friend who was an Olympic alternate in Judo. Myself and another friend “attacked him”. Long story short I ended up in a knee bar and attacker two ended up in a triangle choke.